1. Field of the Invention
The present invention relates to inductors. More specifically, the present invention relates to a variable inductor having a non-magnetic core, and a method of manufacturing same.
2. Related Art
Inductance is a fundamental property of an electrical circuit or circuit element, whereby an electromotive force is induced in the circuit or element as the result of a changing magnetic flux (e.g., a change in magnetic flux due to an alternating current flowing through a coil). Often, it is desirable to change the inductance of a circuit so as to alter the resonant frequency of the circuit. For example, in radio frequency (RF) applications, it is often necessary to tune a circuit to a desired frequency in the radio spectrum. This is often accomplished by altering the inductance of the circuit, using a device known as an inductor.
Inductors can be fixed or variable. A fixed inductor is a coil of wire wrapped around a core, which can either be a dielectric (e.g., air, plastic, etc.) or a metal (e.g., soft iron, etc.). Fixed inductors provide a specific, pre-defined, non-variable level of inductance. Variable inductors, on the other hand, can provide a range of inductance levels, and can be adjusted as desired. One type of variable inductor is a coil of wire wrapped around a dielectric core, and a magnetic, metallic core positioned coaxially within the dielectric core. The position of the core can be adjusted with respect to the coil to alter the resonant frequency of the coil, by rotating the core with respect to the coil.